It has been known that the DCPD-phenol resin is produced by the catalytic reaction of phenolic compound and DCPD in the presence of an acid catalyst of Friedel-Crafts catalyst such as boron trifluoride complex or an ion exchange resin.
However, it has been a problem that the conventional DCPD-phenol resin is colored in dark brown so deeply that the external appearance of molded products is not agreeable and the epoxy resin obtained by reacting the above resin with epihalohydrin is colored in dark brown similarly. When the colored epoxy resin is used as a sealing material, it is difficult to apply marks to resin products, so that work efficiency is lowered seriously.
Therefore, in Japanese Laid-Open Patent Publication No. H07-252349, a method for obtaining light colored resins is proposed, in which DCPD is reacted with phenol using boron trifluoride catalyst at low temperatures for a long period of time. However, even when this method is utilized, the tendency of coloring in hydrocarbon-phenol resin is not always sufficiently reduced. Furthermore, because the reaction takes a long period of time as long as 20 hours or more in total, there is a problem that much labor is required resulting in the increase in production cost.
The primary object of the present invention is, therefore, to provide a process for producing effectively a hydrocarbon-phenol resin having desirable hue or color tone without necessitating a long period of time by reacting phenolic compound with unsaturated cyclic hydrocarbon having two or more carbon—carbon double bonds in the presence of an acid catalyst. Another object of the present invention is to provide a process for producing epoxy resin that is similarly less colored and excellent in color tone, which resin is made by reacting the above phenol resin with epihalohydrin in the presence of a base catalyst.